seems to be able to take on more brightly colored hues without sacrifice to life. But the attitude of butterflies and disposition of color also contribute to this protection.

The distribution of color in butterflies shows that all the brilliant coloring is on the upper surface of all four wings, while the under surface is almost always soberly colored, and often very dark and obscure. The moths, on the contrary, have generally their chief color on the hind wings only, the upper wings being of dull, sombre, and often imitative tints, and these generally conceal the hind wings when the insects are in repose. This arrangement of colors is therefore eminently protective, because the butterfly always rests with his wings raised so as to conceal the dangerous brilliancy of his upper surfaces.

Warning colors are not only possessed by butterflies, but wasps and bees which have stings are often conspicuously colored with yellow and black.

THE PAINTED LADY BUTTERFLY AND ITS WORLD-WIDE DISTRIBUTION

NE of our handsomest butterflies, the Painted Lady, is portrayed in the accompanying plate illustration. This species of butterfly frequents the flowers of the thistle during July, and it is from the almost constant association of these insects with this flower that it is often called the thistle butterfly. This fact also led Linnæus to name it Pyrameis cardui.

In England, where the identical species is found, it is often known as the Painted Lady, in deference to its beautiful colors. Its life history is not without interest. It lays its eggs on several common species of thistle, the burdock, nettle, and marshmallow. The develop

ing larvæ are in consequence of their varied diet characterized as polyphagous. This insect is not alone confined to America and England, but is one of the most cosmopolitan of all the butterflies. It is distributed, according to Holland, over the entire world, with the exception of the arctic regions and the jungles of the Congo in Africa. What, may we ask, are the factors conducive to this wide distribution?

The life of this butterfly, like many others, is exposed to attack by enemies during all the transitional stages, or instars, from the egg to the adult. The eggs, larvæ, and pupæ must in some way survive the effects of parasitism. It is probable that during the migration and dispersal of this species, the egg and pupa parasites did not follow their host at once, but in time the parasites followed. The butterflies were thus at first allowed to multiply more rapidly in the absence of these enemies. Parasites, by becoming numerous, probably create a scarcity of their own food supply. A sort of equilibrium is finally maintained between host and parasite, growing out of various contingencies.

An important factor in aiding the distribution of the Painted Lady is the fact that the food plants, upon which the developing larva depend, were well established prior to the distribution of the butterflies. Its predaceous enemies, such as birds, must be checked by some defensive structures, and these are found on the larvæ in the form of distasteful branched spines. In its migrations it was necessary to adapt itself to the physical changes of climate incident to the wide range of new conditions. The power of flight also, favored by the air currents, aided in this butterfly's dispersal.

The larva's existence on the thistle may be recognized by the silken web which it uses to cover itself, and also for the purpose of forming a little canopy out of a leaf for protection. Here the thistle spines may give it slight immunity from preying birds. The full-grown caterpillar attains a length of about an inch and a half. Its body is striped with black and interrupted lines of yellow. The head is black and the feet reddish. There are seven whitish branched spines, those behind the first segment being tipped with black; these spines form an armature to the body which is distasteful to

The Painted Lady, or Thistle Butterfly (Pyrameis cardui). It is distributed over nearly the entire world.

birds, and the warning colors doubtless function in connection with these spines in thwarting the attacks of birds and lizards.

THE SADDLE-BACK LARVA

F all the queer tenants harbored by the witch-hazel, perhaps the most singular one is the saddle-back larva. It is an August visitor, coming about the middle of the month. A somewhat mutilated leaf, with a ragged margin, may give the first hint of the presence of the larva.

It lives in gregarious colonies when young, and a quainter brood can rarely be found. Fully exposed along the margin and lined up like a company of soldiers, they feed upon the leaf. Gradually this process goes on until only the veins or stems remain. Such a colony as described was found on the witch-hazel. A photographic illustration of this brood shows them in their favorite attitude when eating. They feed on the leaves of many species of trees, including the younger, fresh green underbrush of the oak and basswood, and sometimes they are found on fruit trees.

These caterpillars have short bodies and both ends look alike. Each extremity is provided with a pair of dark spiny tubercles. At the head they are somewhat larger and supplied with supplementary tufts of hair. On the back of the larva is a square green patch, while at the middle there is a purplish brown saddle, surrounded by a ring of white, edged with black.

The larvæ are provided with stinging hairs fringing the sides of the body. On coming in contact with the human body where the skin is thin, they often cause a painful sensation, not unlike that of nettle. It is thought that the hairs break off in the skin, thus producing an irritating effect.

"It is a most suggestive fact," says Wallace, "that in cases where color is required only as a warning, as among the uneatable caterpillars, we find, not one or two glaring tints only, but